Junos OS: Out-of-bounds Read
CVE-2025-21598 is a high-severity out-of-bounds read vulnerability in Junos OS from Juniper Networks, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 21.2R3-S9, 21.4R3-S9, 22.2R3-S5 as the first without the flaw, so updating Junos OS to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.72% chance of exploitation within 30 days, higher than 54% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Junos OS to 21.2R3-S9 or 21.4R3-S9 or 22.2R3-S5 or 22.3R3-S4, whichever matches your release line, or a later version.
- Update Junos OS Evolved to 21.4R3-S9-EVO or 22.2R3-S5-EVO or 22.3R3-S4-EVO or 22.4R3-S5-EVO, whichever matches your release line, or a later version.
- Read the advisory on supportportal.juniper.net for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Juniper Networks | Junos OS | 21.2R3-S8 up to, but not including, 21.2R3-S9; 21.4R3-S7 up to, but not including, 21.4R3-S9; 22.2R3-S4 up to, but not including, 22.2R3-S5; 22.3R3-S2 up to, but not including, 22.3R3-S4; 22.4R3 up to, but not including, 22.4R3-S5; 23.2R2 up to, but not including, 23.2R2-S2; 23.4R1 up to, but not including, 23.4R2-S1; 24.2R1 up to, but not including, 24.2R1-S1, 24.2R2 | 21.2R3-S9, 21.4R3-S9, 22.2R3-S5, 22.3R3-S4, 22.4R3-S5, 23.2R2-S2 |
| Juniper Networks | Junos OS Evolved | 21.4R3-S7-EVO up to, but not including, 21.4R3-S9-EVO; 22.2R3-S4-EVO up to, but not including, 22.2R3-S5-EVO; 22.3R3-S2-EVO up to, but not including, 22.3R3-S4-EVO; 22.4R3-EVO up to, but not including, 22.4R3-S5-EVO; 23.2R2-EVO up to, but not including, 23.2R2-S2-EVO; 23.4R1-EVO up to, but not including, 23.4R2-S1-EVO; 24.2R1-EVO up to, but not including, 24.2R1-S2-EVO, 24.2R2-EVO | 21.4R3-S9-EVO, 22.2R3-S5-EVO, 22.3R3-S4-EVO, 22.4R3-S5-EVO, 23.2R2-S2-EVO, 23.4R2-S1-EVO |
| Juniper Networks | Junos | 21.2; 21.4; 22.2; 22.3; 22.4; 23.2; 23.4; 24.2 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA (juniper.net).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.2 | High | CNA (juniper.net) |
| CVSS 3.1 | 7.5 | High | CNA (juniper.net) |
Official description
An Out-of-bounds Read vulnerability in Juniper Networks Junos OS and Junos OS Evolved's routing protocol daemon (rpd) allows an unauthenticated, network-based attacker to send malformed BGP packets to a device configured with packet receive trace options enabled to crash rpd. This issue affects: Junos OS: * from 21.2R3-S8 before 21.2R3-S9, * from 21.4R3-S7 before 21.4R3-S9, * from 22.2R3-S4 before 22.2R3-S5, * from 22.3R3-S2 before 22.3R3-S4, * from 22.4R3 before 22.4R3-S5, * from 23.2R2 before 23.2R2-S2, * from 23.4R1 before 23.4R2-S1, * from 24.2R1 before 24.2R1-S1, 24.2R2. Junos OS Evolved: * from 21.4R3-S7-EVO before 21.4R3-S9-EVO, * from 22.2R3-S4-EVO before 22.2R3-S5-EVO, * from 22.3R3-S2-EVO before 22.3R3-S4-EVO, * from 22.4R3-EVO before 22.4R3-S5-EVO, * from 23.2R2-EVO before 23.2R2-S2-EVO, * from 23.4R1-EVO before 23.4R2-S1-EVO, * from 24.2R1-EVO before 24.2R1-S2-EVO, 24.2R2-EVO. This issue requires a BGP session to be established. This issue can propagate and multiply through multiple ASes until reaching vulnerable devices. This issue affects iBGP and eBGP. This issue affects IPv4 and IPv6. An indicator of compromise may be the presence of malformed update messages in a neighboring AS which is unaffected by this issue: For example, by issuing the command on the neighboring device: show log messages Reviewing for similar messages from devices within proximity to each other may indicate this malformed packet is propagating: rpd[<pid>]: Received malformed update from <IP address> (External AS <AS#>) and rpd[<pid>]: Malformed Attribute
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other references
Other vulnerabilities in Junos OS
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 7.5 High severity
Recent Out-of-bounds Read vulnerabilities
- 7.5 High severity
- 7.8 High severity
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
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